Any Detroit diesel guys here?

I run a small tugboat at work, powered by two Detroit diesels. The starboard engine fires right up without ether and does not smoke at all. It will run flawlessly all day. The port side engine not only requires a shot of ether each morning, but the exhaust smokes white for several minutes before clearing up. I must give it part throttle for it to stay running, until it is warmed up. I do this by engaging the throttle cable by hand at the engine, then selecting either forward or back once in the wheelhouse.

I plan on changing all filters and fluids one of these weekends, as it has not been done since the company purchased this boat. I doubt this is the issue, but it would give me peace of mind to have fresh oil and filters, as well as fresh fuel filters. After all, this engine did quit on me once just after I used it to push a loaded barge. Anyone here know about these things? I'm not sure about potentially different models, etc. I can get that information this week if necessary.